Hard compositions of matter



Patented July 12, 1938 UNITED STATES FPAr N'r. OFFlCE No Drawing. Original application September 6,

1935, Serial No. 39,505. Divided and this application February 24, 1937, Serial No. 127,558

16 Claims. (Ci. 15-136) This application is a division 01 my pending application for Letters Patent, Serial No. 39,505, Hard compositions of matter, filed September 6, 1935, upon which U. S. Patent No. 2,093,844, is-

.5. sued September 21, 1937, and other divisional applications are filed herewith.

My invention relates to new hard compositions of matter. It has to do, more particularly, with certain novel compositions of matter, notable for their combined strength and hardness, so that they. are particularly useful in the construction of tools, dies and other articles of wear-resisting or corrosion-resisting nature, as well as articles which'are required to resist deformation or' destruction at high temperatures and pressures.

particular, my invention relates to the production of new hard compositions of matter, which are particularly useful as the hard bits or tips including the cutting .edges of tools intended for cutting hard materials. These compositions are also particularly adapted to use as wire-drawing dies.

The principal object of my invention is to provide new hard compositions of matter, which have greater combined strength, hardness and resistance to deformation at high temperatures and pressures than any hard compositions of matter heretofore known.

A further object of my invention is to provide new hard. compositions of matter, having great 9 combined strength, hardness and resistance to deformation, which are made from macro-crystalline carbides of the metals of the group includi ng tantalum and columbium, with, asa minor constituent, one or more of the carbides of the group including tantalum, columbium, titanium and zirconium, which carbides are characterized,

not only by their macro-crystalline form, but by a carbon content in true monatomic ratio .to the metal or metals present. In other words, it is an 49 object of my invention to produce new hard com-' positions of matter, having useful characteristics as indicated, which are made from the new.

macro-crystalline product, instead of the amorphous material heretofore known, for example, as tantalum carbide and consisting of carburized tantalum, in which the carbon is not present im exact 'monatomic ratio to the tantalum.

A further object of my invention is to provide novel hard compositions of matter, having great combined strength and hardness, which include titanium carbide r zirconium carbide, or both of them, as constituents.

It is a further object of my invention to provide novel hard compositions of matter, including tantalum carbide or'columbium carbide, or both ofdesired shape and that pieceheated in an electric them, together with tungsten metal or molybdenum metal, or both, and a metal or metals of the iron group, in which the proportion of the metals of the group including tungsten and molybdenum to the total non-carbide ingredients of 5 the composition is substantially higher than has been possible heretofore without sacrificing strength. This is an important feature, because an increased proportion of tungsten or molybdenum, or both, imparts to the hard compositions 10 of matter the property of resisting deformation, especially at high temperatures, but, heretofore, it has not been possible to include as much tungsten or molybdenum as was desired, because of the deleterious effect upon the strength of the resulting composition.

Further objects, and objects relating to details and economies of production and operation, will definitely appear from the detailed description to follow. In one instance, I accomplish the ob- 20 jects of my invention by the devices and means set forth in the following specification. My invention is clearly defined 'and pointed out in the appended claims. I

Hard compositions of matter have been known, heretofore, which consisted of an amorphous material, called tantalum carbide", together with certain proportionsof a metal or metals of the group including tungsten and molybdenum, and a metal or metals of the group including iron, cobalt and nickel. The best of these hard compositions of matter was, composed as follows: Amorphous tantalum carbide, 7-8 per cent, nickel, 10.2 per cent, tungsten, 11.8 per cent. This material was made by comminuting the amorphous 35 tantalum carbide and metallic tungstenin a ball mill, using nickel balls, in abath of naphtha, until the mixture contained the tantalum carbide, tungsten and nickel in the desired degree, of hueness and in the required proportions above given. 40 The naphtha was then removed entirely by heat ing in a partial vacuum at a red heat. A piece was then formed from this dried powder of the formed is indicated by the fact that the piece,

having a thickness'of .200 inch and a width of .375 inch, resting on supports 11/16 of an inch apart, when pressed in the middle with a one 55 centimeter Brinell ball, broke under a load of 1980 kilograms.

Another example of similar hard compositions of matter, heretofore known, is one which com prised 80 per cent amorphous tantalum carbide, 8 per cent nickel and 12 per cent tungsten. This composition had a. Rockwell A hardness of:

87.75 and broke, under the same conditions Tas specified above, at a load of 1500 kilograms.

These two hard compositions of matter, just-described, represent what I believe to be the most desirable hard compositions of this type heretofore made, known or used.

- These compositions were made from a material which was called ftan'talum carbide, but in which the carbon was not present in exact monatomic ratio to the tantalum. This material was having particles which average less than .01 I

millimeter in largest cross section dimension. I

understand that there is another sense, in which all solid bodies maybe described as crystalline,

and may be shown to have ordered atomic ar- I rangement by X-ray methods, or to have crystalline form which may be seen under the microscope, but I do not use the term in this sense, in

V of the amorphous type in which the carbon is not this specification. I

It will be observed that, in the two compositions above-mentioned, the nickel and tungsten together constitutef22 per cent and 20. percent,

respectively, of the composition, and that the tungsten constitutes 53.6 per cent and 60 per cent, respectively, of the ingredients of the composition other than the. tantalum carbide. I had believed it desirable, if possible, to increase the proportion of tungsten 'in the non-carbide ingredients of the composition, but I had found that this was not-feasible, heretofore, because a further increase in the proportion of tungsten resulted in a decrease in the strength of the composition, which was undesirable, as the piece would break or chip when ,used as a metal cutting tool. Thus, although a higher percentage of tungsten is desirable, in order to give the compoe sition increased resistance 'to deformation, especially at, high temperatures, this increased proportion of tungsten could not be obtained,

heretofore, Without an accompanying decrease in the, strength of the composition.

Hard compositions. of matter have been pro-- posed, heretofore, including columbium carbide,

present in truemonatomic ratio to the columbium, together with certain proportions of tungsten and cobalt, but such hard compositions were .lacking in practical value, because of the weakunited into a cohesive mass by a mixture of metallic iron and molybdenum. Although such,

compositions were hard, they were lacking in strength as they would break under a load which was only about one-third of the breaking load of '1 the amorphous tantalum carbide composition "heretofore referred to. e

. In general, myinvention consists of novel hard compositions of matter made from macro-crystalline carbides of the metals of the group including tantalum and columbium, containing carbon in true monatomic ratio to the metals present. The macro-crystalline multi-carbide forming the starting ingredient for the new composition is comminuted, in a non-oxidizing bath, as by a ball mill, for such length of time as 'needed to reduce the crystals to the desired degree of fineness and to incorporate in the mixture the desired proportions of a metal or metals of the group including tungsten and molybdenum,-

and of a metal or metals of the iron group. The

powdered mixture thus. formed after drying off some of the naphtha is pressed to the shape of the piece to be made, the linear dimensions, however, being from 15.to 25 percent greater than those of the ultimate piece, depending upon the shrinkage which takes place in the process, and the piece thus shaped is heated, under a partial vacuum, in an electric furnace, for about forty minutes, at a temperature of about 1430" C. The heating should require'about two hours in all,

one hour and twenty minutes being consumed in gradually raising the furnace to the ultimate temperature and removing the gas and vapors, and the i'urnace being maintained at the ultimate temperature for about forty minutes. As a result of this treatment, the shaped piece shrinks intoa cohesive bit of like shape, but smaller dimensions, and it is believed that the metal or metals of the group including tungsten and molybdenum, and the metal or metals of the iron group, included in the composition, function to unite the grains ofcarbide into a cohesive mass.

As will be shown hereinafter, the resulting comsitions. 1 The macro-crystalline multi-carbides which I contemplate using in my present invention, and

the method of making such multi-carbides, are

fully described in .my pending application for United States Letters Patent, Serial No. 31,521, filed July 15, 1935, entitled, Carbides of tantalum and like metals and methods of producing the same,"to which cross-reference is hereby made.

The invention of the present application contemplates novel hard compositions of matter embodying macro-crystalline multi-carbidesin which the major constituent is tantalum carbide or .columbium carbide and the minor constituent is formed by a carbide or carbides of a metal or metals ofthe group consisting of tantalum, columbium, titanium andzirconium. My application, Serial No. 39,505, upon which U. S. Patent No. 2,093,844 issued September 21, 1937, isdirected to compositions embodying such a multi-carbide in which the major constituent is tantalum carbide and the minor constituent is formed by carbides of a plurality of metals of the group consisting of columbium, titanium and zirconium.

Two other divisional applications of such application, Serial No. 39,505, are filed herewith, one being directed to hard compositions embodying a macro-crystalline simple carbide, that is, either tantalum carbide or columbium carbide. The other of such divisional applications is directed to compositions of matter embodying multi-carbides of metals of the group consisting of tantalum, columbium, titanium and zirconium in which the major constituent is columbium carbide. I believe that the minor constituent of these multi-carbides is present in solid solution in the major constituent, and this belief is confirmed by the X-ray spectrograms of these multicarbides. My present invention contemplates,

also, new hard compositions of matter including macro-crystalline multi-carbides in which either tantalum carbide or columbium carbide constitutes the major constituent, and one or.more carbides of the metals of the group including tantalum, columbium, titanium and zirconium constitute the minorconstituent. A study of these multi-carbides, also, has shown that the minor constituent is present in solid solution in the major constituent within certain limiting .percentages of the solute. Thus, I contemplate the formation of new compositions of matter from macro-crystalline multi-carbides in which, for instance, titanium carbide or zironium carbide, or both of them, are present in solid solution in tantalum carbide or columbium carbide, and I have found that the hard compositions of matter made from these macro-crystalline multicarbides exhibit a very useful combination of line multi-carbide, in which TaC constitutes the In general, the percentage of multi-carbide contained in my new composition is somewhat,

less than the percentage of tantalum-carbide in the hard compositions of matter heretofore known, such as the two examples previously referred to, but, notwithstanding, the combined hardness, strength and resistance to deformation is greater. In general, also, in my new compositions made inaccordance with this invention, the tungsten or molybdenum, or both, constitute a greater proportion of the non-carbide in- Serial No. 31,521.

gredients of the composition than has been the the worker in this art to believe that an increase in the proportion of tungsten would necessarily weaken the composition.

The following are specific examples of new compositions of matter, made in accordance with my invention, from macro-crystalline multicarbides of the character described in my pending application for United States Letters Patent, In the formulas, given in th s specification, for these multicarbides, I have included in parentheses the symbol or symbols forthe metal or metals, the carbides of which form the minor constituent. It is necessary, in forming hard compositions of matter from these multi-carbides to provide other metals, which I believe perform the function of uniting the grains of multi-carbide to form a cohesive mass and forming a matrix in which the grains of the'hard carbide are embedded. These metals forming major constituent, and CbC the minor constituent. This multi-carbide is expressed by the formula Ta(Cb)C. The CbC may constitute from 1 to 25 per cent of the multi-carbide. In this composition, the Ta(Cb)C may constitute from to 81 per cent of the composition, W, from 13 to 43 per cent, and Ni, from 5 to 15 per cent.

The preferred range of proportions is as follows: CbC, from 5 to 13 per cent of the Ta(Cb)C, Ta(Cb)C, 68 to 80 per cent, W, 13 to '25 per cent, and Ni, 5 to 12 per cent. The specific proportions of an actual specimen of this composition, made from macro-crystalline Ta(Cb)C, in which the proportion of CbC was 8.8 per cent, are as follows: Ta(Cb) C, 75 per cent, W, 15 per cent, and Ni, 10 per cent. Tests upon this specimen showed that it had a Rockwell A hardness of 88.5 and a breaking strength of 2060 kilograms. Thus, in both strength and hardness, this composition was superior to the prior compositions hereinbefore mentioned. Tests upon cutting tools, including bits made from this composition, showed that they were very much better than any heretofore known, in that the tools did not fail, either by deformation, that is mushrooming, or by chipping. Cutting tools made from this composition andv ZrC the minor constituent. The ZrC may constitute from 1 to 23 per cent of the Ta(Zr)C.

' The Ta(Zr)C may constitute from to 80 per cent of the composition, W, from 4 to 20 per cent, and Ni, from 5 to 26 per cent. The preferred range of proportions is as follows: ZrC, from 8 to 13 per cent of the Ta(Zr)C, Ta(Zr) C, from 65 to 80 per cent of the composition, W, from 8 to 18 per cent, and Ni, from 12, to 18 per cent. A specimen of this composition, which has shown verygood results under tests, had thefollowing the matrix may comprise one or more of the -rnetals of i;he group including tungsten and riroiybdenum, and one or more of the metals of the iron group. Small quantities of manganese,

beryllium and aluminum may also, at times, be present with advantageous results. In general,

specific proportions: vZrC, 9 per cent of the Ta(Zr)C, Ta(Zr)C, 74 per cent of the composition, W, 11 per cent, Ni, 15 per cent. This specimen showed a Rockwell A hardness of 88.8,

and a breaking strength of 1887, kilograms. Thus, it was harder than-prior compositions made from 'amorphous TaC, and of comparable strength. Cutting. tests with tools, including bits made of this composition, showed a greater resistance to deformation under high temperatures than the prior compositions made from amorphous tantalum carbide. r

The specific examples of hard compositions of matter, made in accordance with my invention, just given, are illustrative of the new compositions that may be made by the use, as starting materials, of: the macro-crystalline multi-carbides of the character described and claimed in my pending application for United States Let- 5 I have found that a combination of tungsten and nickel serves, inmost circumstances, to form ;the sort of matrix desired.

A valuable .hard composition of matter may! be ters Patent, Serial No. 31,521. It will be understood, of course, that I have not described speciflcal-ly all of the possible combinations. In general, molybdenum may be substituted for all or apart of the tungsten in any of these compositions, it being understood that, in making such substitution, the proportion of the, metal used should be adjusted in theratio of the atomic weights of tungsten and molybdenum. It will be understood, also, that cobalt may be substituted in whole or in part for the nlckebthe proportions being adjusted in the ratio of the atomic weights of cobalt and nickel. Iron may also be substituted for a part of the nickel or cobalt, but the fact that iron, in flnely-dividedform, oxidizes readily, under the conditions present in making these compositions, renders its use in substitution for" all. or a major roportion of the nickel undesirable.

To express the range of proportions of these compositions; I prefer to state the proportions in molecular and atomic percentages of the ingredi- 3 ents. I prefer that the multi-carbide shall constitute from 68.1 to 55.64 ,molecular per cent of the composition, that ametal or metals of the group including tungsten and molybdenum should constitute from 15.5 8 to 17.66 atomic per cent of the composition, and that a metal or metals of the iron group shall constitute from 20.5 to,26.7"'atomic percent of the composition. I prefer, further, that, in'the case of the multicarbides, the minor constituent or constituents shall constitute less than 40 molecular per cent of the multi-carbide, as this is about the maximum which will go into solid solution in the major constituent. -I prefer, however, to use less than the maximum amount of minor constituent,

which would go, into solidv solution in the major constituent, and I havedetermined that it is advantageous to have. the minor constituent constitute about 25 per cent of thefmulti-carbide.

' I believe that, where the ;multi;-carbide is one in which CbC is the major constituent, compositions having a better combined strength, hardness and resistance to'deformation may be producedby substituting molybdenum, inwhole or in part, for the tungsten.

The preferred methods for making'these new compositions of matter are describedln detail and claimed in my pending application for Letters Patent, Serial No. 66,707, Method of pro- .ducing hard compositions of' matter, which likewise isa division of my pending application for vLetters Patent, Serial No. 39,505, .Hard compositions of matter, flled- Septemberffi, 1935, of

-'which the present application is a division. Consequently, the "various steps willnot be described in detail herein.

' bits of the desired shape and of a size such as to H compensate for the shrinkage of 1510-25 per. cent, whichwil l later take place in the heat treatment; The hits, are men 'subjected to beattreatment;"

' :"15' ision gigpro' duced by the reaciion betweenfa In general, the macro-crystalline multi-carbide. is ground and comminuted in a ball ,mill with metallic tungsten or molybdenum, and with nickel, cobalt or iron, the comminution with the metallic ingredients being continued until the ingredients reach the desired state offlneness and until they are present in the proper proportions. The comminution is prei'erably carried out in a bath of naphtha, or other suitable material, to

prevent oxidation; and it is preferable that the naphtha be previously purified-as by subjecting it to ireshlycut'surfaces of sodium, to remove.

oxygen and sulphur-containing compounds.

-The finely comminuted particles are partiallydried, l-to 5 per .centof the naphtha being left to protect the powder from oxidation, and the thoroughly mixed particles are then pressed into under a vacuum of {rem 45 to T microns 0i met";

cury pressure, in an electric furnace, for about forty minutes at a temperature'of from 1400 C.

. to 1500 C., depending upon the ratio of the metals, the temperature being slowly raised until it reaches this temperature. The vacuum is obtained by a Gaede mercury diffusion pump which have as an ingredient a comminuted macrocrystalline multi-carbide including TlC or ZrC, is that, when the TiC or ZrC, or both of them, are in solid solution in the TaC or CbC, they are capable of treatment by processes of powder metallurgy, which would destroy their-surfaces when present alone, in the form of the chemically simple ZrC or TiC. That is to say, the TaC or CbC, in which the ZrC or TiC is dissolved, keeps it from being oxidized or otherwise reacted upon, during the grinding and heat treatments. In-

dicative of this is the fact that 'IiC and ZrC,

per so, cannot be prepared by the method used to produce macro-crystalline TaC, but, when prepared in'solid solution in TaC or CbC, they can be treated with acid, and dried with air, and

preserve an exact monatomic ratio of carbon to metal. v

Another reason for the great utility of the hard compositions of' matter, including a comminuted macro-crystalline 'multi-carbide as an ingredient,

is that such multi-carbides are harder than the simple carbides, following the generalization that all solid solutions are harder than their simple components. This efiect is fundamental and is believed to be due to the straining of the atomic lattice, which is stressed internally by the sub-- stitution of atoms of different atomic radius-in place of the Ta or Cb.

Furthermore, compositions made with macrocrystalline multi-carbides as ingredients generally have lower thermal conductivity, for the strained and harder lattices are poorer conductors. This is an advantage when the composition is used in certain kinds of drawing dies and tools, for, 'in these'casesfa greater proportion of the heat, generated by mechanical work at the point of contact, is distributed to the piece on which thc'work is done. This may be a factor in the successful results obtained in cutting hardened high speed steel with the composition made with comminuted Ta(CbTi)C as an ingredient. the cutting tests of this composition, it was observed that the chips of high speed steel came off at a yellow or white heat, at which tempera- 'ture this steel is soft and workable, although it is still hard at a red heat, unlike steels which do hot have this property of red-hardness. In this specimenof hard composition, the thermal conductivity was observed to be .036 calorie per degree 0., per 'second,,per centimeter, while a j similar composition madewith TaC as the-hard ingredient had a thermal conductivity of i06 Icalorie, per degree C.,.per second,-per centimeter; -Whenever"I use the term macro-crystalline in the appended'claims, with reference to a car-" bideor multi carbide, I mean a carbide or multicarbide having particles which average greater- 1f thaniillmiiliiheter in largesteross section dimenf ,3 Y Q 5 metal or metals and carbon in the presence of a menstruum other than the reactants.

I am aware that the products herein disclosed may be varied considerably, without'demacro-crystalline multi-carbide having,

parting from the spirit of my invention, and,

therefore, I claim my invention broadly as ining of tantalum, columbium, titanium and zirconium, embedded in a matrix formed of an alloy of a metal of the group consisting of tung-' sten and'molybdenum with a metal of the iron group, said particles constituting the major portion of said composition of matter.

2. The new hard composition of matter consisting substantially -of particles of a comminuted macro-crystalline multi-carbide having, as a major constituent, a carbide of the group of metals consisting of tantalum and columbium and, as a minor constituent, a carbide orcarhides of a metal or metals of the group consisting of tantalum, columbium, titanium and zirconium, in which the minor constituent is in solid solution in the major constituent, said carbide particles being embedded in a matrix formed of an alloy of a metal of the group consisting of tungsten and molybdenum with a metal of the iron group, said particles constituting the major portion of said composition of matter.

7 3. The new hard composition of matter consisting substantially of particles of a comminuted macro-crystalline multi-carbide having, as a major constituent,'a carbide of the metals of the group consisting of tantalum and columbium and, as a minor constituent, one or more 01 the carbides of the metals of the group consisting of tantalum, columbium, titanium and zirconi-,

um, in which the minor constituent constitutes about 25 molecular per cent of the multi-carbide, said particles being embeddedin a matrix formed of an alloy of a metal-ofthe group consisting of tungsten and molybdenum with a metal of the iron group, said particles constituting the major portion of said composition of matter.

4. A new hard composition of matter consisting substantially of a matrix formed of an alloy of.a metal of the group consisting of tungsten and molybdenum with'a. metal of the iron group, in which there are embedded particles of a comminuted macro-crystalline multi-carbide including titanium carbide in solid solution in a carbide of a metal of the group consisting of tantalum and columbium, said particles constituting the major portion of said composition of matter.

5. The new hard composition of matter consisting substantially of particles of a comminuted macro-crystalline multi-carbide consisting of tantalum carbide having in solid solution therein one ormore carbides of the group consisting. of columbium, titanium and zirconium, said particles being embedded in a matrix formed oI-an alloy of a metal of the group consisting oi tungsten and molybdenum with a metal of the iron group, said particles constitutingth'e major f portiomofesaidcomposition or matter.

nuted macro-crystalline multi-carbide having tantalum carbide as its-major constituent and,

with a metal of the iron group, said particles constituting the major portion of said composition of matter.

7. The new hard composition of matter consisting substantially of particles of a comminuted macro-crystalline multi-carbide consisting of columbium carbide in solid solution in tantalum carbide, in which the carbon content is in monatomic ratio to the metals present, said particles being embedded in a matrix formed of an alloy of a.- metal of the group consisting of tungsten and molybdenum with ametal of the, iron group, said particles constituting the major portion of said composition of matter.

8. A new hard composition of matter consisting substantially of particles of a comminuted macro-crystalline multi-carbide having tantalum carbide as its major constituent and, as a minor constituent, from 5 to 13 per cent of columbium carbide, the said particles being embedded in a. matrix formed of an alloy of a. metal ofthe group consisting of tungsten and molyb;

' denum with a metal of the iron group, said particles constituting the major portion of said composition of matter.

9. A new hard composition of matter consisting substantially-of from 68 to 80 per cent of a comminuted macro-crystalline multi-carbide, of which tantalum carbide is the major constituent and from 5 to 13 per centcolumbium carbide the minor constituent, from 13 to 25. per cent tungsten, and from 5 to 12 per cent nickel.

10. A new hard composition of matter consisting substantially of 75 per cent of a comminuted macro-crystalline multi-carbide, consisting of tantalum carbide as the major constituent 97nd substantially 9 per cent columbium carbide q as a minor constituent, about 15 per cent tungsten, and about 10 per cent nickel.

11. A new hard composition of matter consisting substantially of a matrix formed of an alloy of a metal of,the group consisting of tungsten and molybdenum with a. metal of the iron group, having embedded therein particles of a.

comminuted macro-crystalline multi-carbide consisting of titanium carbide in solid solution in tantalum carbide, said particles constituting the major portion of said composition of matter.

12. The new hard-compositionof matter consisting substantially of a matrix formed of an alloy of a metal of the group consisting of tungsten and molybdenum with a metal of the iron group, in which are embedded particles ,of a. comminuted macro-crystalline multi-carbide of which tantalum carbide is the major constitu: ant and zirconium carbide is the minor con- :stituent, said particles constituting the major portion of said composition of matter.

13. The new hard composition of matter consisting substantially of a matrix formed of an alloy of a metal of the group consisting of tungsten and molybdenum with a. metalof the iron group, in which are embedded particles of a comminuted macro-crystalline multi-carbide in which zirconium carbide is in solid solution in, tantalum carbide, saidlparticles constituting the 75 major portion of said composition of matter.

14. The new hard composition of matter consisting substantially of a matrix formed 0! an alloy of a metal of the group consisting of tungsten and molybdenum with a metal of the iron group, in which are embedded particles of a comminuted macro-crystalline multi-carbide of which tantalum carbide is the; major constituent and from 8 to 13 per cent otzirconium carbide the minor constituent, said particles constitutingthe major portion of. said composition sisting substantially of from 8 to 18 per cent tungsten, from 12 to 18 pe cent nickel, and from 65 to 80 per cent of a comminuted macro-crystalline multi-carbide having tantalum carbide as its major constituent and, as a minor constitu- .1

eat, from 8 to 13 per cent of zirconium carbide.

16. The new hard composition of matten concent of a comminuted macro-crystalline multicarbide containing about 9 per cent zirconium carbide in solid solution in tantalum carbide.

PHILIP M. MCKENNA. 

